A. K. Kozlov

A high-power semiconductor switch of high-voltage pulses with a rise time of nanosecond duration

The results of studies of new fast-acting semiconductor devices—deep-level dynistors intended for use in high-power devices of nano-and microsecond pulsed-power technology—are presented. The possibility of switching multikiloampere current pulses having a rise rate of 200 kA/μs with the use of a single device with a 12-mm-diameter structure is shown. A high-power switch based on an assembly of dynistors with an operating voltage of 12 kV connected in series is described. The switch is capable of switching current pulses with a 1200-A amplitude and a 4-ns rise time.

Reverse switch-on dynistor switches of gigawatt-power microsecond pulses

A high-power (150 kA and 16 kV) small switch based on an assembly of reverse switch-on dynistors (RSDs) connected in series and a coaxial saturable-core choke, which creates conditions for their efficient switching, is described. An essential feature of this switch is a drastic reduction of the duration of the control action, as a result of which minimum dimensions and a low inductance of the saturable-core choke are ensured at a high (25 kA/μs) rise rate of the switched current. Increases in the control-current amplitude and rise rate that are required for maintaining the triggering charge at a constant level are attained thanks to the use of a fast-acting switch based on new semiconductor devices—deep-level dynistors—in the RSD-control circuit.

Installation for air cleaning from organic impurities by plasma formed by barrier discharge of nanosecond duration

A prototype installation for air cleaning by plasma, which consists of a barrier-type discharge reactor and a high-voltage nanosecond-pulse supply generator, which is based on drift step recovery diodes, is considered. A stable corona-type barrier discharge was obtained at a 3-kHz supply-pulse repetition frequency. The discharge remained nonlocalized even at a small gas-discharge gap (∼6 mm) due to a short (∼25 ns) pulse duration, which allows a quite uniform effect on the air flow. The high rise rate (∼6 kV/ns) of the applied supply voltage pulses determines the high voltage amplitude (∼25 kV) at the reactor at the breakdown moment and allows maintenance of high electric-field intensity and a high intensity of plasma chemical processes. Thus, an electrical power lower than 8 W is required at the reactor input to produce 1 g of ozone per hour. The concentration of methylmercaptan in air during waste-water smell deodorizing at State Unitary Enterprise “Vodokanal of St. Petersburg” was reduced down to an allowable level of 0.5 mg/m3 at the electrical power consumption no higher than 0.25 W per cubic meter of air.

Semiconductor switches of laser pumping pulses of nanosecond duration

Switches of megawatt nanosecond pulses based on high-voltage (12 kV) assemblies of drift step-recovery diodes (DSRDs) and deep-level dynistors (DLDs) are described. Circuit diagrams allowing their use in laser technology are considered. Results of testing of the diode and dynistor switches in power supply circuits of nitrogen lasers at a frequency of 100 Hz are presented. Their high efficiency in shaping of pumping current pulses with a rise time of 10 ns and amplitudes of 500 A (a DSRD switch) and 900 A (a DLD switch) is shown.

High-Voltage RSD Switches of Submegaampere Current Pulses of Microsecond Duration

Two versions of a switch circuit based on an assembly of reverse switch-on dynistors (RSDs) with a 25-kV operating voltage connected in series are described. Their main feature is a decrease in the device dimensions as a result of introducing two successively triggered low-power dynistor units into the control circuit and assembling several RSD structures in a common ceramic housing. The first circuit version is used in the discharge circuit of the capacitive energy storage in the operation into a mismatched load and can switch alternating pulses with a 750-μs duration with amplitudes of the first pulses of the forward and reverse currents of 130 and 15 kA, respectively. The second version employs the crowbar regime and makes it possible to form unipolar current pulses with a 190-kA amplitude and a 500-μs duration in the load circuit.

High-power switches based on reversely switched-on dynistors for high-voltage pulse technologies

The results of comparative investigations of commercially produced reversely switched-on dynistors (RSDs) with an operating voltage of 2 kV and 76-mm-diameter structures are presented. The studies were performed in the mode of switching current pulses with an amplitude of 200 kA and a duration of 300 μs. The electric scheme of the power circuit of the generator of high-power high-voltage pulses with a switch on the basis of an assembly of RSDs is considered. RSD switches with an operating current of 250 kA and operating voltages of 12 and 24 kV are described. Some results of using RSD switches in high-voltage pulse technologies are presented.

High-voltage diode-dynistor switches of high-power alternating current pulses

Electric circuits of high-power switches based on assemblies of diodes that are connected in series to reverse switch-on dynistors (RSDs) are considered. They allow RSDs to be efficiently used in the modes of switching high-power weakly decaying current pulses, which were previously impossible because of high energy losses in dynistors during the reverse-current flow. The results of a comparative study of high-voltage (24 kV) diode-dynistor switches under the conditions of switching current pulses with an amplitude of 50 kA and a damping decrement of 1.3 are presented. The possibility of increasing the switched power is shown.

Semiconductor formers of high-voltage pulses of nanosecond duration

A small former of high-voltage pulses of nanosecond duration based on new semiconductor devices—deep-level dynistors (DLDs)—is described. The former has been developed on the basis of the Marx voltage-multiplication principle and allows formation of 8-kV voltage pulses across an 8-Ω load at a 2.5-kV input-voltage level. A DLD-based former with an output diode opening switch based on assemblies of drift step-recovery diodes connected in series is described. The results of its being tested are presented. Voltage pulses with an amplitude of 25 kV and a rise time of 1 ns are obtained across a 100-Ω load.

A capacitor cell of a capacitive energy storage with a switch based on reverse switch-on dynistors

A capacitor cell of a capacitive energy storage designed for operating with an arc load is described. The cell that stores an energy of 64 kJ is based on a high-voltage (18 kV) capacitor and allows formation of current pulses with an amplitude of up to 60 kA. The discharge circuit of the cell contains a semiconductor switch in the form of an assembly of reverse switch-on dynistors (RSDs) connected in series, a crowbar diode switch, and a replaceable toroidal inductor. An assembly of protecting diodes connected in series to the RSD switch excludes the possibility of a flow of reverse-current pulses through dynistors. All elements of the cell are mounted on the capacitor and occupy a volume of 120 dm3.

A generator of electrical discharges in water

A semiconductor high-voltage pulse generator for the electric-discharge water purification is described. It is based on a low-voltage capacitor storage, step-up pulse transformer, and high-voltage output circuit with a recuperation section returning inefficiently used energy to the power source of the capacitor storage.